Hydraulic engine



magma@ ATTORNEY Feb. 2, 1965 R. N. BENNETT HYDRAULIC ENGINE Filed April a, 195s R. N. BENNETT HYDRAULIC `ENGINE Feb. '2, `1965 4 Sheets-Sheet 2 "Filed April 8, l1963 ROBERT lV. BENNETT I NVENTOR ATTORNEY Feb. 2, 1965 Filed April 8, 1963 R. N. BENNETT HYDRAULIC ENGINE 4 Sheets-Sheet 3 HUBERT /V. BENNETT INVENTOR ATTORNEY Feb. 2, 1965 R. N. BENNETT 3,168,006

HYDRAULIC ENGINE Filed April 8, 1963 4 Sheets-Sheet 4 @#92 ,8a 73 50 $4 N Q) 9| |2 89 9'\ 47 l 4 /87 Fsas 54 4 42 FIG. 7

ROBERT N BENNETT INVENTOR ATTORNEY United States Patent ce 3,168,9b Fatented Feb. 2, 1Q65 3,168,006 HYDRAULRC ENGINE Robert N. Bennett, McCnrnb, Ohio, assigner to The Oilgear Company, Milwaukee, Wis. Filed Apr. 8, 1963, Ser. No. 271,136 7 Claims. (Cl. i1- 176) This invention relates to a hydraulic engine having a plurality of radially extending cylinders and producing relative rotary movement between the cylinders and a crankshaft and, more particularly, to a high torque, slow speed hydraulic engine.

In a typical hydraulic engine of this type, the cylmders apply thrust to an eccentric crankpin which extends with its axis parallel to the axis of the crankshaft and is spaced radially therefrom, the axes of both the crankpin and the shaft extending perpendicularly to the plane of the radially arranged cylinders. Thrust is delivered from the pistons to the crankpin by bearing shoes on the ends of the pistons which slidingly engage the outer surface of the crankpin and power fluid is fed to the cylinders by remote valving means which connects to a separate duct leading to a xed end of each cylinder. Similarly each cylinder is connected to exhaust during its return stroke by the valving` means.

In this type of construction, extremely high unit bearing pressure exists between the surface of the piston bearing :shoes and the rotating crankpin. Because of the slow speed of rotation and the interruption of any lubricating `film at the edges of the bearing shoes, lubrication therebetween is not easy to maintain and this results in a high frictional resistance to sliding movement of the shoes on the crankpin and a high resistance to rotation with a resulting loss in mechanical eiciency.

The valving means, which usually is rotary, also requires a suiiicient running clearance between the rotating :and stationary elements to prevent excessive friction and 'this causes a slippage of power fluid from the high to the low pressure side of the valve and a considerable loss in the hydraulic elliciency of the engine. A separate rotary valve which is usually used also requires space in the engine housing, absorbs some power in order to be actuated, and increases the weight and cost of the engine.

In a hydraulic engine constructed according to the present invention, each cylinder is alternately connected to power fluid and exhaust by valve means that includes the crankpin andcomrnunicates directly between the piston thrust shoes and the crankp'in, the power iiuid source and exhaust both being connected through passages in the crankshaft, and crankpin to such valving means.

It is the principal object of the instant invention to provide a hydraulic engine of the type briefly described wherein the use of an external valve is eliminated.

It is another object of the instant invention to provide, in a hydraulic engine of the type described herein, wherein the valving means includes a cylindrical port ring or sleeve mounted circurnjacent the crankpin and functioning `to connect the interior of the cylinders to Valve ports formed inthe crankpin.

It is yet another object ofthe instant invention to provide surface conligurations for the piston bearing shoes and for the crankpin whereby the surface friction between the individual cylinder bearing shoes and the port sleeve and between the port sleeve and `the crankpin is a minimum.

It is a still further object' Vof the instant invention to reduce the surface friction between the individual cylinder bearing shoes and the circular port sleeve mounted circumjace'nt the crankpin by cutting away substantially all of the bearing surface of the bearing shoes except for a marginal,

` sealing `portion`ofsufcient area to withstand the thrust Vforces involved'and to s'eal olic the central portions of the shoes through which power and exhaust fluid pass er1 route to and from their respective cylinders.

It is another object of the invention to provide valve means formed on the external surface of the crankpin for controlling communication between an annular port ring or port sleeve circumjacent the crankpin and fluid passageway/s in the interior of the crankpin, these valve means being alternately in communication with each of the ports in the port ring which are in constant communication with the cylinders, and the surface of the crankpin is cut away to form suitable vaive ports and in order to provide desired pressure balancing between the crankpin and the port ring.

It is a further object of the invention to provide an engine of the type described having an annular port ring mounted circurnjacent t'o the crankpin and provided with individual ports for each of the cylinders and with means for controlling the translation of the port ring and retaining it lagainst rotation relative to the housing so as to constantly maintain communication between the ports of the port ring and the respective cylinders of the engine through the piston shoes.

Another object of the invention is to provide cooperating vaiving means on the periphery of the crankpin and on the individual cylinder shoes whereby during rotation of the crankshaft and crankpin, the cylinders of the engine are successively connected to power huid and disconnected therefrom with at least one of the cylinders being connected by the port means to power fluid at all times to insure the constant application of torque to the crankpin and to the crankshaft.

Other objects and advantages of a hydraulic engine embodying the invention will be better understood from the specification and from the drawings in which:

FiG. 1 is an end view in elevation of a hydraulic engine embodyingV the invention and shows a portion of the housing broken away and shows a portion of the exposed engine parts in section to show the radial arrangement of the pistons and cylinders on the crankpin and the distribution of iiuid therebetween;

FIG. 2 is a cross-sectional view taken along the line 2--2 of FIG. l and shows the engine in cross-sectional elevation;

FiG. 3 is a View on an enlarged scale of the lower piston-cylinder assembly of FIG. 2;

FG. 4 is an isometric view on an enlarged scale show ing the journal portion ofthe crankshaft and its crankpin and the journal portion of the housing for the hydraulic engine shown in FIG. l to show the iiuid conducting passages therein;

FiG. 5 is an isometric view of a bearing shoe for a piston or" the machine of FIG. 1 to show the bearing face of the shoe;

FIG. 6 is a sectional view taken along an irregular section line 66 in FIG. 2 to illustrate the arrangement of the linkage means that secures the port ring against rotation relative to the housing; and

FIG. 7 is a sectional view similar to that of FIG. 6 and includes the lower piston-cylinder section and housing of the machine in FIG. 2 with the crankpin displaced 90 degrees to show the pivotal swing of the lower pistoncylinder assembly which remains in radial alignment on the crank pin.

The piston engine 10 shown in FIGS. 1 and 2 has a crankshaft 11 that includes a crankpin 12 whose axes are parallel to each other and their spacing or eccentricity being determinative of the stroke of the engine.

A housing for the engine includes a star-shaped housing portion 14 and a journal housing portion 16. The housing portion 16 is provided with axially spaced thrust and radial bearings 17, 18 secured in annular recesses withinthe housing. The'crankshaft, which is inserted into the housing from the left end in FIG. 2, is journalled in the bearings 17, 1S. The crankshaft 11 has an enlarged flange 19 at its inboard end which has a lip or disc-like flange 2t) that abuts the lower race of bearing 17, and near the f outboard end where the crankshaft is of further reduced diameter it is journalled in bearing 1S. A bearing adjusting nut 21 is suitably secured to the outboard end of the crankshaft 11 as by threaded engagement therewith and locked as by a setscrew to the crankshaft. The bearing adjusting nut 21 abuts the outboard end of the inner race of bearing 18 to thereby axially secure the crankshaft 11 within the bearings 17, 18. An oil seal vring 22 is provided in the end of the journal housing 16 for sealing engagement with the clamping ring 22.

The stepped configuration of the crankshaft permits convenient insertion and removal of the crankshaft from the journal housing through a large opening in star-shaped housing portion 14 which is shown closed by a removable cover 15.v

The crankshaft 11 also includes the crankpin 12 preferably formed integral therewith. The crankpin 12 is a cylindrical member that extends axially from shaft flange 19 yand olf-center therewith to provide a crank whose throw or stroke is double the eccentricity of its axis with respect to the axis of the crankshaft 11. The crankpin 12 is formed with a shoulder 13 at its juncture with the shaft flange 19 and crankpin 12 extends into the star-shaped housing for rotation with the crankshaft in an orbit about the axis of the crankshaft.

The crankpin 12 is provided with diametrically opposite valve ports 26, 27 formed in the cylindrical surface of the crank pin, as best seen in FIG. 4. Machine ports 28, 29

are provided in the journal housing 16 for the supply and y discharge of motive fluid. These ports 28, 29 connect rej they are connected respectively by radial holes 36, 37 to the Valve ports 26, 27. These axially extending passages 33, 34 are inclined because of the offset between the crankshaft and its crankpin, and they are connected respectively by radial holes 38, 39 in the crankshaft to the annular grooves 30, 31 for establishing communication between machine ports 28, 29 respectively, and valve ports 26, 27. The inclined axially extending passages 33, 34 in the crankshaft are side by side as seen in FIG. 4 and appear as one above the other in FIG. 2.

A port ring or port sleeve 40, FIGS. l, 2, 6, and 7, is closely fitted on the crankpin 12 in axial abutment with the shoulder 13 formed on crankpin 12 adjacent shaft flange 19. An end plate 23, FIG. 2, secured by screws 24 to the end face of crankpin 12 loosely secures the port sleeve 46 on the crankpin 12 between the end plate 23 and the shoulder 13 to permit relative rotation between the port sleeve 48 and the crankpin 12. The port sleeve 40 is secured against rotation relative to the housing by linkage means 86, FIG. 6, which permits a translatory movement of the port sleeve 48 in the housing as the port sleeve orbits the axis of the crankshaft upon rotation of the crankshaft 11 and crankpin 12.

The port sleeve 40 has ve radial holes, equally spaced fcircumferentially, which serves as cylinder ports 41 through 45 in communication with live radially arranged cylinders 46 in the star-shaped housing 14. Each cylinder port 41 through 45 alternately registers with the valve ports 26, 27 upon rotation of the crankpin 12.

Five piston-cylinder assemblies 51 through 55 are supported in the star-shaped housing 14 and each includes one cylinder 46, a piston 47, and a piston shoe or bearing shoe 48 supported on the end of the piston for transmitting radial thrust between the piston and the port sleeve 46 so that the crankpin 12 produces torque on crankshaft 11.

The bearing shoes 43 are retained on the port sleeve 40 by a pair of retainer rings 49, Si) which permit movernent of the shoes on the port sleeve. Retainer ring 49 is press lit on a shoulder of the port sleeve 40 at its end adjacent the crankpin shoulder 13. Retainer ring 50 is secured to the other end face of the port sleeve 40 by dowel pins 56 press lit in holes therefor.

A spherical headed plug 61 is fitted to the radially outer end of the cylinder 46 and is secured thereto by an annular weld 62. A mating spherical surface 63 is provided in a housing cap 64 for abutment with the end of the cylinder and may be provided by an insert seat, not shown, suitably formed and secured in the housing cap 64. A pair of rocker pins 66 are tightly fitted in holes 67 in opposite sides of the housing cap 64 in alignment with each other and are secured against outward movement by spring washers 68 tted in counter bores for the holes 67. The cylinder 46 has rocker pin receiving recesses or holes 69 of slightly larger diameter than the diameter of the rocker pin recesses. The axis of the rocker pins 66 extends through the pivot center of the mating spherical surfaces of the supporting housing and the cylinder 46 and is transverse to the radial plane of the cylinders 46 to provide a pivot means for swinging movement of the piston-cylinder assembly within such radial plane and to provide universal movement on the cylinder seat for self adjustment of the assemblies on the port sleeve 40.

Piston 47 in cylinder 46 is a hollow piston as provided by a bore 71. The radially outer end of the piston remains within cylinder 46 'and when fully contracted defines a space for pressure fluid behind the piston. Piston rings 74 are provided in the outer surface of the piston for sealing engagement with the cylinder.

Each bearing shoe 4S is generally rectangular, FIG. 5, with a concave cylindrical bearing surface 76 which seats on the cylindrical surface of the pont sleeve 40. A cylindrically extending portion 77 of bearing shoe is in a counterbore 73 in the radially inner end of the piston 47, FIGS. 1, 2 and 7, and the shoulder 7S of the bearing shoe 48 defined by the cylindrical portion seats on the end surface 79 of the piston 47. An oil seal ring 81 is provided on the cylindrical portion 77 of the bearing shoe 48 for sealing engagement with the wall of the counterbore 73. Diametrically opposite shoe pins 82, inserted through pin receiving holes 83, in the piston, are forced into pin receiving holes in the cylindrical portion of the bearing shoe 40 to secure the bearing shoe on the end of the piston. The pin receiving holes 83 are slightly over-size relative to the diameter of the shoe pins 82. The axis of the shoe pins 82 is in the plane of the piston-cylinder assemblies so as to permit seating of the bearing shoe 48 longitudinally of the port sleeve 40. The bearing shoe 48 abuts the end surface 79 of the piston which surface is curved from a crown tarea radially adjacent the shoe pins 82 and therefrom the end surface 79 is inclined preferably about one degree to provide a flat surface. The curvature of the end surface 79 is such as to permit limited rocking of the bearing shoe 48 in a plane transverse to the axis of rocker pins 66. The shoe pins 82 for the bearing shoe are secured with some radial play or lost motion in their pin receiving holes 83 in the piston 47 to permit the rocking motion of the shoe on the end of the piston and to assure that all of the thrust of the piston is transmitted between the end surface 79 of the piston and surface 78 of the shoe.

The bearing shoe 48 has a central bore 84 for passage of motive uid therethrough. The bearing surface 76 is centrally recessed to form a relatively large pocket 85 to provide a lluid bearing with the port sleeve 40.

Rotation of the crankshaft 11 carries with it the crankpin 12 in a circle about the axis of the crankshaft. The

port sleve 40 is carried by the crankpin 12 and the port sleeve is tied by linkage means 86 to the housing 14 so that the port sleevedoes not rotate relative to the housing; the crankpin therefore rotates within the port sleeve once for each revolution of the crankshaft. The linkage means 86 tying the port sleeve to the housing is a cross-slide device comprising a pair of transversely disposed guide rails 87, 88 and a cross-slide member 89. Guide rail 87 is secured by flush mounted screws 91 through the retaining ring 50 to port sleeve 40 for movement therewith. Guide rail 88 is secured by screws 92 to the end cover 15 for the housing 14. Crosssilide member 89 has a slot 93 for receiving guide rail 87 and a slot 94 in the opposite face of the cross-slide member for receiving guide rail 88. The cross-slide member 89 freely slides on guide rail 88 and permits rail 8'7 to freely slide within slot 93 to thus permit translatory movement of the port sleeve 40; the vertical component of such movement, as seen in FIGS. 6 and 7, carries cross-slide member 89 along guide rail 88, and the horizontal component of such movement carries rail 87 along rail slot 93 in the cross-slide member 89.

` For operation of the hydraulic motor, the machine ports 28, 29 are connected to a source of pressure fluid such as a reversible variable displacement hydraulic pump, not shown. Pressure fluid supplied to machine port 28 is conducted through the shaft through passage 33 to valve port 26 formed in crankpin 12. From valve port 26, the pressure fluid is distributed through those cylinder ports in port sleeve 40 that are in communication with valve port 26. There are five piston-cylinder assemblies and the port sleeve provides tive cylinder ports 41 through 45 which are in constant communication wtih the bearing shoes for the piston-cylinder assemblies. The surface portion of the crankpin 12 between the valve ports 26, 27 is a bridge or land 96, FIG. 4, which extends circumferentially at least as much as each cylinder port 41 through 45 so that a cylinder port centered ou a land does not interconnect the two valve ports 26, 27. The valve ports 26, 27 include portextensions provided by drilled holes 97 at the middle of the adjacent edges of the valve ports, so that on relative rotation of the crankpin 12 and port sleeve 40, the cylinder ports cross the lands at the port extensions.

FIGS. 1, 2 and 4 show that motive uid in valve port 26 is supplied through cylinder ports 41, 42 to their associated cylinders 46 of assemblies 51, 52 whose pistons 47 provide a thrust on the crankpin 12 to rotate the shaft 11. ln this same position FIG. l, cylinder ports 44, 45 are connected to the other valve port 27 to return luid from their associated cylinder 46 to machine port 29. In this position, cylinder port 43 is centered on one bridge or land 96 between the valve ports. As the shaft 11 rotates, two cylinder ports and then three cylinder ports alternately register with the high pressure valve port 26, while simultaneously therewith three cylinder ports and then two cylinder ports alternately register with the return or low pressure valve port 27.

Pressure of motive fluid in a cylinder 46 acts on its piston 47 tending to extend the piston and cylinder assembly and produces a thrust on the crankpin 12. Fluid pressure in pressure port 26 in the crankpin 12 acts on the port sleeve 40 to produce a force tending to move the port sleeve radially away from the pressure port area of the crankpin 12. This force is opposed by the thrust force acting on the port sleeve 40 by the pistons 37 whose cylinders 46 are operatively connected to the pressure port 26. The force acting between the port sleeve and the crankpin due to pressure in pressure port 26 is determined by the effective area of the pressure pont 26 which is made so that such force is on the order of eighty percent of the resultant thrust force when tangential to the path of the axis of the crankpin and as exerted by the pistons on the port sleeve. The thrust of the pistons thus holds the port sleeve in sealing engagement with a boundary surface of pressure port 26 in crankpin 12, so that the boundary surface or land area about pressure port 26 is a boundary lubricated bearing surface permitting sliding engagement between the crankpin 12 and the port sleeve 40. Thus, the balance area of the valve ports in the crankpin 12 each have an effective area subject to pressure uid to produce an opposing force to, and less than, the resultant tangential force exerted by the pistons to maintain sealing engagement about each one of the valve ports under pressure with a minimum of frictional drag between the port sleeve and the crankpin 12. Taking into account the eccentricity of the cnankpin 12 to the shaft 11, which is coaxial to the piston-cylinder assemblies, the balancing force thus provided between the crankpin 12 and the port sleeve 49 is on the order of eighty percent of the effective resultant tangential thrust force of the pistons which may be resolved as greater than the :thrust force of a single piston. This determines then that the pressure area of pressure port 26 is slightly greater than the area of the bore of one cylinder 46, and this ratio provides the desired pressure balance whether two or three cylinders 46 are operatively connected to the pressure port 26.

Each bearing shoe 48 is also pressure balanced to a predetermined extent on the port sleeve 40 to maintain a boundary lubricated surface 76 for the land area of the shoe surrounding its bearing pocket 85. The bearing surface 76 of such land area of the shoe is therefore made of suitable material for sliding and thrust transmitting engagement with the mating surface of the port sleeve. The area of bearing pocket is therefore proportioned to theu area of the bore of a cylinder 46 to provide about eighty percent of the force urging the shoe against the port ring so as to provide a positive force holding the piston shoe in sealing engagement with the port sleeve. The pressure area of the bearing pocket of the bearing shoe is therefore substantially less than the area of the bore of the cylinder 46. Such predetermined unbalance therefore provides a` lubricated bearing surface that permits sliding movement between the piston shoe and the port sleeve so that each piston-cylinder assembly can maintain itself in radial alignment with the crankpin 12 with a minimum of frictional drag therebetween.

The bearing shoe 48 is shown in FIG. 5 to have a cylindrical bearing surface 76 interrupted by the duid receiving bearing pocket 85 to provide a uid bearing area, and such bearing surface 76 is also shown interrupted by a pair of grooves 98 which extend circumferentially across the face of the bearing on opposite sides of the bearing pocket 85. These grooves 9S serve as drain grooves which limit the surface area of the bearing face to a desired predetermined effective pressure area to avoid separation of the bearing surfaces.

Rotation of the crankshaft 11 and the eccentric crankpin 12 due to thrust of working pistons 47 requires the piston-cylinder assemblies to change their radial position so as to remain radi-.ally aligned with the axis of the crankpin 12. This can be seen from a comparison of FIGS. l and 7 Where piston-cylinder assembly 53 in FIG. l is radially aligned with both the axis of the crankpin 12 and the axis of lthe crankshaft 11, and in FIG. 7 the piston-cylinder assembly remains aligned only with the axis of the crankpin 12. The latter position shows the maximum swing position of the piston-cylinder assembly 53, which is evident because the axis of the crankpin 12 now lies in a horizontal plane with the axis of the crankshaft 11. Each piston and cylinder combination thus oscillate from side to side within the radial plane of piston-cylinder assemblies for each revolution of the crankshaft 11, while each piston-cylinder is extended and then contracted.

Such oscillatory motion results in .the bearing shoes each sliding on the port sleeve 40 to keep the pistonalsace@ cylinder assemblies 51 through S5 in radial alignment with the crankpin 12. Pistons 47 urged by high pressure from valve port 26 to transmit thrust are readily held thereby in radial alignment with the crankpin l2. The other pistons 47 whose cylinders are connected to the return valve port 27 are also urged by low fluid back pressure lin their cylinders toward the crankpin 12 for maintaining radial alignment therewith.

FIG. 7 shows that the bearing pocket 85 in the bearing shoe 48 extends circumferentially a sufficient extent to remain in constant communication with its associated cylinder port, which is cylinder port 43 for the lower piston-cylinder assembly 53.

The hydraulic machine has been described as being supplied with pressure fluid to engine port 28 and the return of pressure fluid from engine port 29. Such supply of pressure fluid will cause one direction of rotation of the crankshaft. Reversing the supply and return of pressure fluid will provide an opposite direction of rotation -to the crankshaft 11, as is Well known.

The hydraulic machine has thus been described as a motor with a rotating crankshaft 11. The principal function, however, remains the same, if the crankshaft and crankpin 12 are stationary supports for the machine and the housing is permitted to rotate about the axis of the crankshaft. In an application of the latter function, the crankshaft 11 would serve as a stationary axle and the star-shaped portion of the housing would serve as a mounting for la vehicle wheel. In this type of application, the uid supply and return passages in the crankshaft are extended axially through the crankshaft to ports `in the end thereof.

While but one embodiment of the invention has been shown and described, further embodiments or changes herein may be made by one skilled in the art without departing from the spirit of the invention and the scope of the appended claims.

I claim:

l. In a hydraulic engine having a housing, a crankshaft mounted in and for rotation relative to said housing; a crankpin having a generally cylindrical surface and carried by said crankshaft with the center line of said crankpin parallel to and spaced radially from the axis of said crankshaft, and at least three equally spaced, radial, cylinder assemblies mounted with their center lines being normal to the axis of rotation of said crankshaft, the improvement comprising, in combination, cooperating pivot means mounted on said housing and said cylinder assem` blies at the outer end of each of said cylinder assemblies, a piston in each of said cylinder assemblies, two diametrically opposed circumferentially separated valve ports in the surface of said crankpin which dene two diametrically opposed and axially extending lands in the surface of said crankpin, two fluid passageways extending through said crankpin and each communicating with one of said valve ports, and said fluid passageways being open to inlet and outlet ports, respectively, in said housing, an annular port ring rotatably mounted on and in bearing circumjacency with said crankpin, said port ring having .an axial width greater than the axial extent of said valve ports, radial ports in said port ring, one for each of said cylinders and being equally spaced circumferentially, an individual, arcuate, pressure shoe mounted on the inner fend of each of said pistons and bearing on the outer sur- :face of said port ring, each of said pressure shoes having :a central and radially extending port therethrough, a fluid passageway leading from the interior of each cylinder and communicating through the central port of the respective one of said pressure shoes with the respective one of the radial ports in said port ring, and guide means connected to said port ring for restraining said port ring against rotation relative to said housing and for guiding said port ring in a circular path of translation relative to said housing upon rotation of said crankpin, said guide means com- CII prising a cross-slide guided in one direction on said port ring and in a transverse direction on said housing.

2. A radial piston hydraulic machine comprising a housing, a crankshaft journalled in said housing, a crankpin carried by said crankshaft, a pair of valve ports in a cylindrical surface of the crankpin, a port sleeve journalled on the crankpin and having radially arranged cylinder ports which alternately register with the valve ports upon relative rotation of the crankpin and port sleeve, a plurality of piston and cylinder units radially arranged in the housing for swinging movement for maintaining radial alignment with the crankpin, a bearing shoe on each piston and cylinder unit having a flow through passage in continuous registration with an associated said cylinder port for conducting motive fluid between cylinder units and valve ports, and guide means connected to the port sleeve comprising a cross-slide guided in one direction on the port sleeve and in a transverse direction on the housing for guiding the port sleeve in a circular path of translation relative to the housing while restraining the port sleeve against rotation relative to the housing.

3. A hydraulic engine having a housing, a crankshaft rotatable relative to said housing, a drive flange of relatively large diameter carried by said crankshaft, an overhung crankpin of relatively small diameter carried by said drive flange and spaced from the axis thereof, said crankpin having diametrically opposite valve ports formed in a cylindrical surface thereof and connected to inlet and outlet fluid passages extending from the crankpin through the drive flange and into the crankshaft, a port sleeve journalled for rotation on said crankpin and provided with radial passages serving as cylinder ports adapted to alternately register with the valve ports, guide means connected to the port sleeve comprising a crossslide guided in one direction on said port sleeve and in a transverse direction on said housing for preventing rotation of the port sleeve relative to the housing, a plurality of radially arranged cylinder assemblies secured at their radially outer ends to the housing by pivot means whose axes are parallel to the crankshaft to permit the cylinder assemblies to swing in their radial plane for maintaining radial alignment with the crankpin, said cylinder assemblies being closed at their radially outer ends and at their radially inner ends having concave cylindrically faced bearing shoes for sealing engagement with the port sleeve, each of said bearing shoes having a relatively large central fluid bearing recess in its bearing face open to a flowthrough passage for conducting motive fluid to and from the interior of a cylinder of a piston and cylinder assembly, said central duid bearing recess being constructed and arranged so that said bearing shoe is held in sealing engagement with the port sleeve with the bearing recess in continuous registration with a cylinder port in the port sleeve throughout the oscillatory pivotal movement of the piston and cylinder assembly.

4. A hydraulic machine as defined in claim 3 in which the valve ports formed in the crankpin are constructed and arranged to establish a pressure field area on the adjacent face of the port sleeve that effects a separating force between the crankpin and port sleeve that is slightly overbalanced by the thrust forces exerted by the bearing shoes against the port sleeve for holding the port sleeve in uid sealing engagement with the outer surface of the crankpin bordering a pressure one of said valve ports.

5. A hydraulic engine having a housing, a crankshaft rotatable relative to said housing, an overhung crankpin carried by said crankshaft and having diametrically opposite valve ports formed in a cylindrical surface of the crankpin and connected to inlet and outlet fluid passages within the crankshaft, a port sleeve journalled for rotation on said crankpin and provided with cylinder ports adapted to alternately register with the valve ports, a plurality of radially arranged cylinder assemblies secured at their radially outer ends to the housing by pivot means whose axes are parallel to the crankshaft to permit swing movement of the cylinder assemblies only radially of the crankpin for maintaining radial alignment therewith, said cylinder assemblies being closed at their radially outer ends and presenting tubular openings at their radially inner ends, bearing shoes having cylindrical stud portions telescoping with the tubular ends of the cylinder assembiies and secured together by wobble pins which permit limited wobble movement of the bearing shoes transverse to the swing movement of the cylinder assemblies, said bearing shoes having concave cylindrical bearing surfaces with ilow through recesses for registering with cylinder ports in the port sleeve for conducting motive fluid between valve ports and cylinder assemblies while transmitting thrust to the crankpin, `and guide means connected to the port ring comprising a cross-slide guided in one direction on said port ring and in a transverse direction on said housing for preventing rotation of the port ring relative to the housing.

6. A hydraulic engine having a housing, a crankshaft journalled in said housing and having an axially interiorly positioned drive ange of relatively large diameter carrying an overhung crankpin of relatively small diameter, axially spaced radial bearings supporting said crankshaft at said drive ange and adjacent an outboard end of said housing, said crankpin having a cylindrical surface with diametrically opposite valve ports formed therein and connected to inlet and outlet iiuid passages extending through the crankpin, drive ange and crankshaft for connection to ports for the machine, a port sleeve journalled on said crankpin and having radial passages serving as cylinder ports adapted to alternately register with the valve ports, said valve ports constructed to provide a predetermined mean field area with said port sleeve, guide means connecting the port sleeve to the housing and preventing rotation of the port sleeve relative to the housing upon rotation of the crankpin relative to the port sleeve, a plurality of radially arranged cylinders pivotally supported in the housing at their radially outer ends, tubular pistons in said cylinders, bearing shoes on the free ends of said pistons and having concave cylindrical bearing faces for making sealing engagement with the port sleeve, each of said bearing shoes having a central recess in the bearing face and a ilow through passage for conducting rnotive fluid between the cylinder and cylinder port in the port sleeve, said piston and bearing shoe having an effective area subject to uid pressure in the cylinder such that the effective thrust exerted by the cylinders under pressure is slightly greater than the opposing force exerted on the port sleeve by the pressure port on the predetermined field area on the internal surface of the port sleeve, whereby the port sleeve is maintained in sealing engagement with the surface of the crankpin bordering the pressure port therein.

7. The machine as deiined in claim 6 in which said bearing shoes oscillate on said port sleeve as said crankshaft rotates, retainer rings disposed coaxially on said port sleeve and having annular ange portions overlying axially opposite sides of said bearing shoes in close relation to said port sleeve and limiting radial separation of said bearing shoes from said port sleeve.

References Cited in the tile of this patent UNITED STATES PATENTS 735,684 White Aug. 4, 1903 2,594,288 Button Apr. 29, 1952 2,687,118 Bennett Aug. 24, 1954 3,006,324 Shaw a Oct. 31, 1961 3,030,932 Muller Apr. 24, 1962 3,036,557 Kimsey May 29, 1962 3,040,716 Hahn llune 26, 1962 

1. IN A HYDRAULIC ENGINE HAVING A HOUSING, A CRANKSHAFT MOUNTED IN AND FOR ROTATION RELATIVE TO SAID HOUSING; A CRANKPIN HAVING A GENERALLY CYLINDRICAL SURFACE AND CARRIED BY SAID CRANKSHAFT WITH THE CENTER LINE OF SAID CRANKPIN PARALLEL TO AND SPACED RADIALLY FROM THE AXIS OF SAID CRANKSHAFT, AND AT LEAST THREE EQUALLY SPACED, RADIAL, CYLINDER ASSEMBLIES MOUNTED WITH THEIR CENTER LINES BEING NORMAL TO THE AXIS OF ROTATION OF SAID CRANKSHAFT, THE IMPROVEMENT COMPRISING, IN COMBINATION, COOPERATING PIVOT MEANS MOUNTED ON SAID HOUSING AND SAID CYLINDER ASSEMBLIES AT THE OUTER END OF EACH OF SAID CYLINDER ASSEMBLIES, A PISTON IN EACH OF SAID CYLINDER ASSEMBLIES, TWO DIAMETRICALLY OPPOSED CIRCUMFERENTIALLY SEPARATED VALVE PORTS IN THE SURFACE OF SAID CRANKPIN WHICH DEFINE TWO DIAMETRICALLY OPPOSED AND AXIALLY EXTENDING LANDS IN THE SURFACE OF SAID CRANKPIN, TWO FLUID PASSAGEWAYS EXTENDING THROUGH SAID CRANKPIN AND EACH COMMUNICATING WITH ONE OF SAID VALVE PORTS, AND SAID FLUID PASSAGEWAYS BEING OPEN TO INLET AND OUTLET PORTS, RESPECTIVELY, IN SAID HOUSING, AN ANNULAR PORT RING ROTATABLY MOUNTED ON AND IN BEARING CIRCUMJACENCY WITH SAID CRANKPIN, SAID PORT RING HAVING AN AXIAL WIDTH GREATER THEN THE AXIAL EXTENT OF SAID VALVE PORTS, RADIAL PORTS IN SAID PORT RING, ONE FOR EACH OF SAID CYLINDERS AND BEING EQUALLY SPACED CIRCUMFERENTIALLY, AN INDIVIDUAL, ARCUATE, PRESSURE SHOE MOUNTED ON THE INNER END OF EACH OF SAID PISTONS AND BEARING ON THE OUTER SURFACE OF SAID PORT RING, EACH OF SAID PRESSURE SHOES HAVING A CENTRAL AND RADIALLY EXTENDING PORT THERETHROUGH, A FLUID PASSAGEWAY LEADING FROM THE INTERIOR OF EACH CYLINDER AND COMMUNICATING THROUGH THE CENTRAL PORT OF THE RESPECTIVE ONE OF SAID PRESSURE SHOES WITH THE RESPECTIVE ONE OF THE RADIAL PORTS IN SAID PORT RING, AND GUIDE MEANS CONNECTED TO SAID PORT RING FOR RESTRAINING SAID PORT RING AGAINST ROTATION RELATIVE TO SAID HOUSING AND FOR GUIDING SAID PORT RING IN A CIRCULAR PATH OF TRANSLATION RELATIVE TO SAID HOUSING UPON ROTATION OF SAID CRANKPIN, SAID GUIDE MEANS COMPRISING A CROSS-SLIDE GUIDED IN ONE DIRECTION ON SAID PORT RING AND IN A TRANSVERSE DIRECTIONON SAID HOUSING. 